Single-bolt joint for feeder and plug-in bus ducts

ABSTRACT

A projection on one side of each splice plate of the stacked joint assembly cooperates with an open-ended, L-shaped slot in the end of the corresponding bus bar to retain the joint assembly in place during assembly of a bus duct run and also secure the bus bars from sliding within the bus duct housing. An insulated sleeve, surrounding the bolt which extends through the stacked assembly, has an oval cross section and fits into a similarly shaped central aperture in each insulator plate. Each insulator plate has at least one raised rib portion wich is concentric with its central aperture. The outer insulator plates are keyed to respective end plates, positioned on the opposite ends of the stacked assembly, by a projection fitting into an indentation in the end plate. The raised rib portion of the insulator plates cooperates with an oval aperture in the splice plates to prevent relative rotational movement therebetween, thereby insuring tbe insulator and splice plates are properly oriented for installation of the joint assembly onto a duct section.

United statesmen 1191 Koenig et al.

[ Jan. 15, 19,74

[ SINGLE-BOLT JOINT FOR FEEDER AND PLUG-IN BUS DUCTS lnventors: MartinF. Koenig; George A.

Dempsey, Jr., both of Milwaukee, Wis.; Manuel Issa, deceased, late ofMilwaukee, Wis; Patrick T. Sheedy, administrator, Fox Point, Wis.

Cutle Wis.

Filed: Mar. 22, 1972.

Appl. No.: 237,070

[73] Assignee: r-Hammer, Inc Milwaukee,

r 7 References Cited j UNITED STATES PATENTS 5 19 8 Vorgensenet al. 3392213 5/1968 2 Vorgensen-etal. 339/22 8 3,180,924 47 19651-Rowe-..;...l.,...:.. 243912213 Primary ExaminerMarvin A. Champion AssistantExaminer-Robert A. Hafer Attorney-John W. Michael et al.

[57] ABSTRACT A projection on one side of each splice plate of thestacked joint assembly cooperates with an openended, L-shaped slot inthe end of the corresponding bus bar to retain the joint assembly inplace during assembly of a bus duct run andalso secure the bus bars fromsliding within the bus duct housing. An insulated sleeve, surroundingthe bolt which extends through the stacked assembly, has an oval crosssection and fits'intoa similarly shaped centralaperture in eachinsulator plate. Each insulator plate has at .least one raised ribportion wich is concentric with its central aperture. The outerinsulator plates are keyed to respective end plates, positioned on theopposite ends of the stacked assembly, by a projection fitting into anindentation in the end plate. The raised rib portion of thev insulatorplates'cooperat es with an oval aperture in the splice platesto preventrelative rotational movement therebetween, thereby insuring tbeinsulator and splice plates are properly 'o riented'for installation ofthe joint assembly'ontoa duct section.

, 901mm,; Drawing Figures ii 60 i It I e f 4a" o 50 4s 70 14 5sSINGLE-BOLT JOINT FOR FEEDER AND PLUG-IN BUS DUCTS BACKGROUND OF THEINVENTION This invention relates to electric busway assemblies and, moreparticularly, to joint assemblies for connecting bus duct sectionstogether.

Busway systems are used for distribution of electrical power,particularly for higher power systems. These systems typically utilizefeeder ducts which include a plurality of parallel bus bars disposedwithin an elongated housing. The feeder ducts are manufactured insection lengths for convenience in handling, transportation andinstallation. The duct sections are mounted end-to-end with the bus barsof adjacent sections being electrically connected together by a jointassembly. Also, plug-in duct sections adaptable for one or more powertap-offs can be connected to each other or to feeder duct sections inthe same manner. A bus duct run usually includes several sections, somany joint connections must be made.

In order to facilitate installation and to insure a proper connectionwith all the bus bars, single bolt joint assemblies have been developed.These joint assemblies employ a single bolt, surrounded by an insulatedsleeve, which extends through and holds a stack of adjacent pairs ofconductive splice plates and interleaved insulator plates. Bus bars ofthe adjacent duct sections are inserted between the opposite ends ofadjacent pairs of the splice plates with the bolt loosened. The bolt isthen tightened to compress the assembly together and provide a tightengagement between the splice plates and corresponding bus bars. Becauseof manufacturing tolerances, the bolt must be quite loose duringinstallation so there is sufficient spacing between the pairs of spliceplates to permit unrestricted insertion of all the bus bars of theadjacent duct section.

During a typical installation of a bus duct run, the joint assembly isinstalled to one end of the bus section which is to be connected to asection previously installed. As the duct section is moved into placefor connection, the loosely installed joint assembly tends to fall offunless some means is provided for retaining it to the bus bars. It isdesirable that this retaining means permit the joint assembly to beremoved from a duct section after installation without completedisassembly of joint members. When the through bolt is untightened forinstallation of the joint assembly onto a bus duct section, the spliceplates and insulator plates generally are free to rotate. Consequently,they frequently become disoriented during handling and must be carefullyreoriented before the joint assembly can be installed onto a ductsection, thereby complicating the assembly operation. Also, the busbars, which normally are not fastened to the duct housing, tend to shiftlongitudinally during handling and/or shipping.

SUMMARY OF THE INVENTION An object of this inventionis to provide athroughbolt joint assembly which is arranged so the insulator and spliceplate are always properly oriented for installation onto a bus ductsection.

Another object of this invention is to provide such a joint assemblywhich can be installed onto one end of the bus section and retained inplace so it will not tend to fall off during assembly of a bus duct run.

A further object of this invention is to provide such a joint assemblywhich can be easily removed from a duct section without completedisassembly of the stack joint members.

A still further object of this invention is to provide a joint assemblywhich, when fastened to the end of a bus duct, will secure the bus barsfrom sliding within the duct housing.

According to this invention, the insulative sleeve means surrounding thethrough bolt, the central opening in the insulator plate means intowhich the sleeve fits, the raised rib portion on the insulator platemeans adjacent to its opening, and the central opening in the spliceplate means into which the rib portion of the insulator plate means fitsare all provided with a noncircular shape and cooperate to preventrelative rotational movement between the splice plate means and theinsulator plate means when the through bolt is untightened forinstallation of the joint assembly onto a bus duct. This arrangementprevents the splice plate means and insulator plate means from becomingdisoriented during handling of the joint assembly.

Preferably, the joint assembly includes outer cover plates positioned onthe opposite outer flat sides of the stacked plates and the insulatorplate means adjacent thereto are provided with means for locking themtogether against relative rotational movement when the through bolt isuntightened. This insures this splice plate means and the insulatorplate means are always oriented with the cover plates.

In another embodiment, the bus bars are provided with an open-ended slotat their ends which cooperates with a nib on the splice plate means torestrain the joint assembly against longitudinal movement and therebyprevent it from falling off the end of a bus duct during handling andsecure the bus bars from sliding longitudinally with the housing.Although capable of retaining the joint assembly in place, thisarrangement permits the joint assembly to be removed after installationwithout completely disassembling the joint members, as is the case withmany prior art arrangements.

BRIEF DESCRIPTIONOF THE DRAWINGS FIG. 1 is a top, plan view of thesingle-bolt joint assembly of this invention shown connected betweenfeeder duct sections.

FIG. 2 is a cross sectional view of the joint assembly taken along theplane designated 22 in FIG. 1.

FIG. 3 is a top plan view of the joint assembly taken along the planedesignated 33 in FIG. 2.

FIG. 4 is a top plan view of an insulator plate.

DESCRIPTION OF THE PREFERRED EMBODIMENT The single-bolt joint assemblyof this invention can be used for connecting feeder duct sectionstogether, plug-in duct sections together, or connecting plug-in ductsections to feeder duct sections. For purposes of description, it willbe described for connecting two feeder duct sections together.

Referring to FIGS. 1 and 2, feeder duct sections l0, 12 are electricallyconnected together end-to-end through joint assembly 14. Feeder ductsections l0, 12, which are identically constructed, include a pluralityof flat, elongated bus bars 16 disposed in an elongated housing 18. Busbars 16 are arranged in side-by-side, sandwiched relationship within thehousing, but are flared out to a spaced, parallel arrangement at eachend to fit into the joint assembly. Housing 18 includes upper and lowerchannel assemblies 20, 22 to which a pair of side plates 24, 26 aresecured in a conventional manner. US. Pat. No. 3,639,676, assigned tothe assignee of the present invention, describes an exemplary generalarrangement for the bus bars and housing.

Joint assembly 14 includes a stack of a plurality of insulator plates28a, 28b, 280, a plurality of adjacent pairs of conductive splice plates30 interposed between the insulator plates, and top and bottom endplates 32, 34. The insulator, splice and end plates are all generallyrectangular. The stack is held together by bolt 36 extendingtherethrough and nut 38 threadably mounted to the bolt. Bolt 36 issurrounded by an insulated sleeve 40 which fits inside a centralaperture in each of the insulator plates. Spring washers 42, 44 arepositioned beneath bolt head 46 and nut 38, respectively, adjacent tothe corresponding cover plate. Bushing 48, positioned inside washers 42,44, include an annular recess in which O-ring 50 is captured against thecorresponding cover plate to provide a moisture seal.

When joint assembly 14 is installed as shown in FIG. 2, the ends of busbar 16 of the duct sections 10, 12, respectively, extend between theopposite ends of corresponding adjacent pairs of splice plates 30. Bolthead 46 is captured by bracket 52 (which is mounted to top end plate 32)so that, by simply tightening nut 38, the stack is compressed and thesplice plates are clamped into electrical engagement with the bus barsto provide an electrical connection between corresponding bus bars ofsections l0, 12. The top and bottom channel assemblies 20 and 20 includebrackets 20a and 20b, respectively, which are attached at their oppositeends to make the transition from the channels to end plates 32 and 34.The end plates are fastened to these brackets by tap screws 53 or thelike. The sides of the joint assembly are closed by side plates 55, 57which are moutned to duct side plates 24, 26 respectively.

As shown in FIGS. 2 and 3, each splice plate 30 has a pair ofprojections 54 located on either side of center which serve as limitstops forthe end of the bus bars 16 as they are inserted. Nib 56,provided on one side of the splice plate 30 and spaced outwardly fromstop projections 54, cooperates with open-ended, L-shaped slot 58 in theend of each bus bar 16 to retain joint assembly 14 against longitudinalmovement after installation. To assemble a bus duct run, the end ofjoint assembly 14 with nibs 56 is first installed onto one end of ductsection 12. Joint assembly 14 is initially positioned off center withrespect to the bus bars so that nibs 56 are guided through thelongitudinal leg of slots 58 as the splice plates are slipped over theouter ends of the bus bars. After the bus bars engage stop projections54, joint assembly 14 is centered and nibs 56 are moved into a lockedposition in slots 58 as shown in FIG. 3. Thus, joint assembly is securedto the ends of duct section 12 so the duct can be moved into place forinstallation of the other end of joint assembly onto the end of ductsection without the joint assembly falling off. Even though providing aneffective means for holding the joint assembly in place forinstallation, this arrangement permits the joint assembly to be removedfrom a duct section without complete disassembly of the joint stackmembers. Preferably, both ends of the bus bars for each duct section areprovided with slots 58 so that the end joint assembly having the lockingfeature can be installed on either end of a duct section.

When one end of end plates 32 and 34 are fastened to respective brackets20a, 20b by screws 53, the bus bars are prevented from shiftinglongitudinally by the cooperation of nibs 56 and slots 58. Thus, with ajoint assembly mounted to one end, a bus duct section can be handledand/or shipped without the risk of the bus bars shifting even thoughbolt 36 is loosened.

As shown in FIGS. 3 and 4, insulative sleeve 40 is oval shaped and fitsinto an oval central aperture 60 in insulator plates 28a, 28b, 280. Eachof the inner insulator plates 28b have a raised rib portion, including apair of ribs 62, 64 which are concentric with aperture 60 on theopposite surfaces, while outer insulator plates 28a and 28c have ribs62, 64 only on the bottom and top surfaces, respectively. Ribs 62, 64are arranged to provide the required over-the-surface electricalclearance between bus bars 16. The raised rib portion of the insulatorplates fit into a central aperture 66 in the splice plates. As shown inFIG. 2, outer insulator plates 28a and 28b are keyed to cover plates 32,34, respectively by projections 68, 70 which fit into small indentations72, 74 provided in the corresponding cover plate on the opposite sidesof center. Thus, the insulated sleeve, insulator plates, splice platesand over plates are interlocked to prevent relative rotational movementbetween the stacked parts, thereby insuring proper orientation of theinsulator and splice plates for installation of the joint assembly ontothe bus bars of a duct section.

From the above detailed description, it can be seen that the jointassembly of this invention can be easily installed onto a feeder duct orplug-in duct section and retained in place during assembly of bus ductrun. The joint assembly can be removed, after loosening the bolt, bysimply moving it laterally so that projection 56 can be guided outthrough the longitudinal leg of slots 58. Also, the cooperation ofoval-shaped apertures of the splice plates and the outer ribs of theinsulator plates insures that the stacked parts are always maintained inthe proper orientation, even when the through bolt is loosened forinstallation of the joint assembly onto a duct section. In addition itcan be seen that the bus bars are secured from sliding movement in busway housing.

We claim:

1. In combination, a first and a second bus duct, each including aplurality of bus bars, and a joint assembly interposed said ducts andelectrically connecting individual bus bars of said first duct tocorresponding individual bus bars of said second duct, said jointassembly comprising a plurality of adjacent pairs of generally flat,elongated splice plate means having a first central opening and arrangedin stacked relationship, the end portions of individual correspondingbus bars of said first and second ducts being interposed respectivepairs of said splice plate means;

a plurality of generally flat, elongated insulator plate means having asecond central opening and arranged in stacked relationship withindividual ones being positioned adjacent the opposite outer sides ofeach pair of said splice plate means, said insulator plate means havinga raised rib portion, concentric with and adjacent to said secondopening, closely fitting inside said first opening;

a bolt means extending through said second opening; said bolt means whentightened urging said pair of splice plate means into contact pressurewith the corrsponding bus bars to establish electrical connectiontherebetween; and

an insulator sleeve means closely fitting inside said second opening andinterposed said'bolt means, said sleeve means, said rib portion and saidfirst opening having complementary, non-circular shapes forcooperatively interlocking said splice plate means and said insulatorplate means so as to prevent substantial relative rotational movementtherebetween when said bolt means is sufficiently loosened to permitlongitudinal movement of said bus bars relative to said splice platemeans.

2. The combination according to claim 1 including a pair of end platemeans positioned adjacent the opposite outer flat sides of the stack ofsplice plate means and insulator plate means with said bolt meansextending through said end plate means; and

means locking said each of end plate means to the adjacent insulatorplate means so as to prevent substantial relative rotational movementtherebetween when said bolt is sufficiently loosened to permitlongitudinal movement of. said bus bars relative to said splice platemeans.

3. The combination according to claim 2 wherein said locking meanscomprises I i an outwardly extending projection on each of the insulatorplate means adjacent to said end plate means, said projections beinglocated in opposite transverse directions from the longitudinal axis ofsaid bolt means and an indentation in each of said end plate means foraccommodating the corresponding projection.

4. The combination according to claim 1 wherein said first and secondopenings, the outer portion of said sleeve means and said rib portionsare all oval-shaped.

5. The combination according to claim 4 wherein each of said bus barsinclude an open-ended, L-shaped slot in the outer end portion; and

at least one of each pair of said splice plate means includes a niblocated transversely from the longitudinal axis of said bolt means whichcooperates with said slot, when said joint assembly is installed to oneend of one of said ducts, to restrain longitudinal movement of saidjoint assembly.

6. The combination according to claim 5 wherein at least one of saidpair of splice plate means includes at least two projectionstransversely offset in opposite directions from the longitudinal axis ofsaid bolt means for limiting the inward longitudinal movement of saidbus bars.

7. The combination according to claim 5 including a pair of end platemeans positioned adjacent the opposite outer flat sides of the stack ofsplice plate means and insulator plate means with said bolt extendingthrough said end plate means;

each of said bus ducts having a housing in which said bus bars aredisposed; and

means for fastening the opposite ends of said end plates to respectiveduct housings, said nibs, slots and fastening means cooperating so that,when said joint assembly is installed to said one end of said duct, thebus bars are secured against substantial longitudinal movement withrespect to said housing, even though said bolt means is sufficientlyloosened to permit the insertion of bus bars between respective pairs ofsaid spliced plate means.

8. In combination, a first and a second bus duct, each including aplurality of bus bars, and a joint assembly interposed said ducts andelectrically connecting individual bus bars of said first duct tocorresponding individual bus bars of said second duct, said jointassembly comprising a plurality of adjacent pairs of generally flat,elongated splice plate means having a first central opening and arrangedin stacked relationship, the end portions of individual correspondingbus bars of said first and second ducts being interposed respectivepairs of said splice plate means;

a plurality of generally flat, elongated insulator plate means having asecond central opening and arranged in stacked relationship withindividual ones being positioned adjacent the opposite outer sides ofeach pair of said splice plate means, said insulator plate means alsohaving a raised rib portion, concentric with and adjacent to said secondopening, closely fitting inside said first opening;

a bolt means extending through said second opening; said bolt means whentightened urging said pair of splice plate means into contact pressurewith the corresponding bus bars to establish electrical connectiontherebetween; and

an insulator sleeve means closely fitting inside said second opening andinterposed said bolt means,

each of said bus bars including an open-ended, L-

shaped slot in the outer end portion; and

at least one of each pair of said splice plate means including a niblocated transversely from the longitudinal axis of said bolt whichcooperates with said slot, when said joint assembly is installed to oneend of one of said ducts, to restrain longitudinal movement of saidjoint assembly.

9. The combination according to claim 8 wherein at least one of saidpair of splice plate means includes at least two projectionstransversely offset in opposite directions from the longitudinal axis ofsaid bolt means for limiting the inward longitudinal movement of saidbus bars.

1. In combination, a first and a second bus duct, each including aplurality of bus bars, and a joint assembly interposed said ducts andelectrically connecting individual bus bars of said first duct tocorresponding individual bus bars of said second duct, said jointassembly comprising a plurality of adjacent pairs of generally flat,elongated splice plate means having a first central opening and arrangedin stacked relationship, the end portions of individual correspondingbus bars of said first and second ducts being interposed respectivepairs of said splice plate means; a plurality of generally flat,elongated insulator plate means having a second central opening andarranged in stacked relationship with individual ones being positionedadjacent the opposite outer sides of each pair of said splice platemeans, said insulator plate means having a raised rib portion,concentric with and adjacent to said second opening, closely fittinginside said first opening; a bolt means extending through said secondopening; said bolt means when tightened urging said pair of splice platemeans into contact pressure with the corrsponding bus bars to establishelectrical connection therebetween; and an insulator sleeve meansclosely fitting inside said second opening and interposed said boltmeans, said sleeve means, said rib portion and said first opening havingcomplementary, noncircular shapes for cooperatively interlocking saidsplice plate means and said insulator plate means so as to preventsubstantial relative rotational movement therebetween when said boltmeans is sufficiently loosened to permit longitudinal movement of saidbus bars relative to said splice plate means.
 2. The combinationaccording to claim 1 including a pair of end plate means positionedadjacent the opposite outer flat sides of the stack of splice platemeans and insulator plate means with said bolt means extending throughsaid end plate means; and means locking said each of end plate means tothe adjacent insulator plate means so as to prevent substantial relativerotational movement therebetween when said bolt is sufficiently loosenedto permit longitudinal movement of said bus bars relative to said spliceplate means.
 3. The combination according to claim 2 wherein saidlocking means comprises an outwardly extending projection on each of theinsulator plate means adjacent to said end plate means, said projectionsbeing located in opposite transverse directions from the longitudinalaxis of said bolt means and an indentation in each of said end platemeans for accommodating the corresponding projection.
 4. The combinationaccording to claim 1 wherein said first and second openings, the outerportion of said sleeve means and said rib portions are all oval-shaped.5. The combination according to claim 4 wherein each of said bus barsinclude an open-ended, L-shaped slot in the outer end portion; and atleast one of each pair of said splice plate means includes a nib locatedtransversely from the longitudinal axis of said bolt means whichcooperates with said slot, when said joint assembly is installed to oneend of one of said ducts, to restrain longitudinal movement of saidjoint assembly.
 6. The combination according to claim 5 wherein at leastone of said pair of splice plate means includes at least two projectionstransversely offset in opposite directions from the longitudinal axis ofsaid bolt means for limiting the inward longitudinal movement of saidbus bars.
 7. The combination according to claim 5 including a pair ofend plate means positioned adjacent the opposite outer flat sides of thestack of splice plate means and insulator plate means with said boltextending through said end plate means; each of said bus ducts having ahousing in which said bus bars are disposed; and means for fastening theopposite ends of said end plates to respective duct housings, said nibs,slots and fastening means cooperating so that, when said joint assemblyis installed to said one end of said duct, the bus bars are securedagainst substantial longitudinal movement with respect to said housing,even though said bolt means is sufficiently loosened to permit theinsertion of bus bars between respective pairs of said spliced platemeans.
 8. In combination, a first and a second bus duct, each includinga plurality of bus bars, and a joint assembly interposed said ducts andelectrically connecting individual bus bars of said first duct tocorresponding individual bus bars of said second duct, said jointassembly comprising a plurality of adjacent pairs of generally flat,elongated splice plate means having a first central opening and arrangedin stacked relationship, the end portions of individual correspondingbus bars of said first and second ducts being interposed respectivepairs of said splice plate means; a plurality of generally flat,elongated insulator plate means having a second central opening andarranged in stacked relationship with individual ones being positionedadjacent the opposite outer sides of each pair of said splice platemeans, said insulator plate means also having a raised rib portion,concentric with and adjacent to said second opening, closely fittinginside said first opening; a bolt means extending through said secondopening; said bolt means when tightened urging said pair of splice platemeans into contact pressure with the corresponding bus bars to establishelectrical connection therebetween; and an insulator sleeve meansclosely fitting inside said second opening and interposed said boltmeans, each of said bus bars including an open-ended, L-shaped slot inthe outer end portion; and at least one of each pair of said spliceplate means including a nib located transversely from the longitudinalaxis of said bolt which cooperates with said slot, when said jointassembly is installed to one end of one of said ducts, to restrainlongitudinal movement of said joint assembly.
 9. The combinationaccording to claim 8 wherein at least one of said pair of splice platemeans includes at least two projections transversely offset in oppositedirections from the longitudinal axis of said bolt means for limitingthe inward longitudinal movement of said bus bars.